MYCETOZOA IN EPPING FOREST IN 1949-50 283
(Fr.) Rost., the late additions to the list were species that are more or less
uncommon, viz: Didymium trachysporum G. Lister, Comatricha rubens Lister,
Trichia affinis de Bary (infrequent in the southern part of the Forest) and
Perichaena vermicularis (Schw.) Rost. B. panicea is not usually an uncommon
species, and I attribute its absence from the list in the eleven months, March
1949 to January 1950 inclusive, to the weather.
In January an abnormal form of Badhamia utricularis (Bull.) Berk.
developed in masses on a decayed hornbeam log, which bore several species
of fungus but neither Stereum hirsutum Pers. nor Polystictus versicolor Fr.
The plasmodium of B. utricularis emerged in quantity but not all at the same
time. Apparently it did not feed superficially in any notable extent, and
most of the sporangia were formed on the log, but part of the plasmodium
travelled to the edge on the log and beyond and formed sporangia on bramble
stems and leaves. Many sporangia were not of the normal ashy grey colour ;
some remained the dark colour they have when maturing and some became
light brown or fawn; many stalks were greyish white rather than straw
coloured. Instead of being subglobose or ovoid, some sporangia were
pyriform or turbinate and contained little lime in the walls ; the capillitia
were often feeble and meagre in amount, and the spores in some cases were
light in colour and poorly warted. The thin walls and light coloured spores
in my opinion accounted for the fawn coloured sporangia. Examination
of several gatherings of this development, including some typical sporangia,
convinced me that the large colony was B. utricularis, and that much of it
possibly suffered from the absence of its usual food. The sporangia on
bramble, i.e. those which had come from plasmodium which had travelled
farthest, were the most abnormal. This log has also produced Arcyria
ferruginea Sauter, Trichia varia Pers., Lycogala epidendrum (L.) Fr. and
Ceratiomyxa fruticulosa (Mueller) Macbr.
In Epping Forest small developments of B. utricularis are found from
time to time on hornbeam without the usual fungi on which it feeds being
present. . Such developments presumably have fed on fungus in or beneath the
bark ; they form sporangia at or near the point of emergence and are normal.
The Craterium leucocephalum found at the Warren, Loughton, in Decem-
ber was an unusual form. Instead of having a lid to the cup, the sporangia
broke irregularly across the top. A form having the same character occurred
in this area during the last war. The late Miss G. Lister was away from
Leytonstone at that time, but when she returned I showed her the specimen
and she agreed that it was var. scyphoides Lister. This happened some time
after the form was found, and it was not recorded as it might have been
merely an unusual development. As it has been found a second time I am
inclined to record it as the variety which is reported from Southern France,
South Africa, U.S.A., and the Galapagos Islands.
Colloderma oculatum (Lippert) G. Lister developed amongst moss and
lichen on a beech log in October. At the end of December it reappeared
on the old oak log where it was first observed about thirty-five years ago.
Considering the vicissitudes the log has met in so frequented a place as Epping
Forest, I think this a remarkable experience ; decay has partly eaten into the
log, leaving ridges, and Colloderma sometimes favours the sides of the ridges
for its development.
During the winter Didymium difforme, D. squamulosum and D. laxifila were
plentiful in leaf beds near the Warren, Loughton ; D, anellus was frequent and
Physarum bitectum, Diderma effusum and D. deplanatum were also found there.
The year's experience indicated that the summer drought was much more
detrimental to the development of leaf inhabiting species than to those matur-
ing on decayed wood, and that leaves under holly trees were slower to become
productive than those amongst brambles and ivy growing on the ground
under deciduous trees.